/***********************************************************************
 * BinTrotter : BitTorrent library/client for the Android operating system.
 *  
 * Copyright (C) 2009, Christopher David Stones (chris.stones@gmail.com)
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************/

package org.bintrotter.afiles;

import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import org.bintrotter.afiles.Files;

public class Hasher {

	public static boolean SHA1(int piece, Files files) throws NoSuchAlgorithmException, IOException {
		
		MessageDigest md = MessageDigest.getInstance("SHA-1");

		MappedByteBuffer[] mbb = files.mmap(piece);
			
		for(MappedByteBuffer b : mbb)
			md.update(b);
	
		for(int i=0;i<mbb.length;++i)
			mbb[i]=null;
		mbb=null;
		
		return Arrays.equals( md.digest(), files.metafile.pieceHash(piece));
	}
}
